ABC News(WASHINGTON) — President Barack Obama said Monday the outcome of the U.S. election leaves him with “concerns” and many missed Donald Trump’s unforeseen victory.

“There was a lot of folks who missed the Trump phenomenon….that connection that he was able to make.. that was impervious to events that might have sunk another candidate, that’s powerful stuff,” Obama said in his first press conference since the historic 2016 election in which it seemed certain Hillary Clinton would win. “What’s clear was that he is able to tap into yes the anxieties but also the enthusiasm of his voters in a way that was impressive.”

While he promised his administration is working with President-elect transition team, as he took questions from the press for the first time since the historic 2016 presidential election, Obama did issue reservations about Trump’s temperament which have many at home and around the world uncertain. Obama said the presidency often magnifies any personal weakness.

“There are going to be certain elements of his temperament that will not serve him well unless he recognizes them and corrects them.”

He talked about his own inability to keep track of “stacks of briefing books” and so he has surrounded himself with “people who can help,” and he hopes Trump does the same.

“The people have spoken. Donald Trump will be the next president,” Obama said. “It will be up to him to set up a team that will serve his policies.”

He said while the election matters, about 43 percent of the country who were eligible to vote did not do so, and that Trump is going to have to blance what he said in the campaign with working with those who disagree with him.

“Because of the nature of the campaigns, and the bitterness and the ferocity of the campaigns, that it’s really important to try to send some signals of unity, and to try to reach out to minority groups and women and others that were concerned about the tenor of the campaign,” Obama said.

Obama added, “It is important for us to let him make his decisions.” And in the end, the American people will judge “if they like what they see,” he said.

Obama said that he has offered the advice to Trump that “campaigning is different than governing” and that he felt Trump is “sincere” in wanting to move the country forward.

“[Trump] is going to try and make sure he delivers” to both his supporters and to those who voted for his opponent Hillary Clinton, Obama said. He added that it is important for Trump to reach out about those needing reassurance.

“People will still be looking to the United States. Our example will still carry great weight,” he said.

Asked what he thought about Stephen Bannon’s appointment as chief strategist, Obama declined to comment, citing his desire for a smooth transition of power. “I think it’s fair to say that it would not be appropriate for me to comment on every appointment that the president-elect starts making if I want to be consistent with the notion that we’re going to try to facilitate a smooth transition.”

In talking with Trump last week, Obama said he learned the incoming administration is committed to maintaining the role the U.S. plays with NATO and its allies.

“In my conversation with the president-elect, he expressed a great interest in maintaining our core strategic relationships and so one of the messages I will be able to deliver is his commitment to NATO and the Transatlantic Alliance,” Obama said.

Later Monday, Obama will depart on his final foreign trip as commander-in-chief and will make stops in Europe and Peru.

Obama added that his administration has “stabilized the American economy” and will continue to do so as the hand-off to President-elect Trump and his team occurs.

Trump has previously stated he would dismantle some of the president’s top initiatives once elected.

“This office is bigger than any one person, and that’s why ensuring a smooth transition is so important,” Obama said.

“The learning curve always continues,” he added of the presidency. “This is a remarkable job; it is like no other job on Earth and it is a constant flow of information, challenges, and issues. That is true now more than it ever has been.”